I love Broken Sword! They're among my favourite games of all time, though the second one disappointed me a little. I really liked the character of Khan for some reason. Oubier was also nice and his fate touched me a lot.
I'm actually one of the few people who didn't mind the box puzzles. They were fun to solve, definitely better than the annoying "press the right button before you die!" puzzles.
I've got high hopes for BS4 as well. The graphics didn't look that good, but everyone is saying that they aren't final, so I guess it's okay. Besides, graphics don't matter as long as the story is good. I hope we get to see some characters from the previous games. I'm keeping my fingers crossed for Ultar and Bronson. It would also be interesting if we got to see the sister Khan mentioned briefly, too.
Scorpicus, you live in England, right? They have released the first two games in a double-pack some time ago over there. You shoul find it at Play.com or something for a really low price.